Method for coating with tin and tin alloys articles made of aluminium or aluminium alloys



MKGHELE N". SALVATI, 0F TUEIN, ITALY; GUIDO BEER AND AltlhlIGrO TEDESCO,EXECULORS 0F "WILL 0F SAID MICHELE N. SA.LV.LTI, DECEASED, ASSIGNURS TO-SGOIETA ANUNIMA STABILIMENTI BIAK, OF TURKEY, I'Iihlh'll.

METHUD F033, CQA'IIN "WITH TIN AND TIN ALLOYS ARTICLES MADE 0F ALUMINIUGR ALUMINIUM ALLOYS.

No brewing.

To all whom it may concern.-

Be it known that l, ldici-innn N. SALVATI, subject of the King of Italy,and resident of Turin, Italy, have invented certain new and usefulMethods for Coating with Tin and Tin Alloys Articles Made of Aluminiumand Aluminium Alloys, of which the following is a specification.

This invention has for its object a method by means of which a coatingof tin and tin alloy may be applied on articles or parts made ofaluminium or aluminium alloys, despite of the known property ofaluminium that tin is-unalole to adhere thereto.

According this invention, the surface of the article made of aluminiumor aluminium alloy on which tin is to he applied, is previ ously coatedwith a layer of another metal capable of adhering firmly to aluminiumand aluminium alloys without giving rise to an electrolytic action whenin contact with aluminium, said coating metal being of such nature thattin and tin alloys adhere to it, As an example of said coating metals,copper, nickel, iron, zinc or the like may be mentioned 5 iron has in aparticular manner said re quired character and the electrolytic processmay be advantageously adopted for coating with it the aluminium andaluminium alloy surfaces on which tin is finally to be applied.

To this end the surface to he coated is firstly cleaned by means of asolution of sodium hydrate and then is Washed with water and is causedto act as a cathode'into an electrolytic hath of an iron salt, by way ofexample into a solution of ferric sulfate; a proper quantity of ammoniumoxalate may be advantageousl added to said bath in order to increaseomogeneousnes's, cohesion and adherence of the iron layer or coatingthus obtained.

As has been found by tests, satisfactory results are obtained by usingan electrolytic hath. comprising a mixture of equal portions of twosolutions the first of them being formed of 4:0 grames of ammoniumoxalate dissolved into 1000 grams of water and the other one consistingof grams of ferric sulfate dissolved into 1000 grams of water; anelectric current having a density of 0.15 ampere for each squaredecimeter of cathode may be conveniently used. A

When an iron layer having the desired Specification of Letters Patent.

thickness is obtained, the surface thereof is washed with Water anddried with sawdust; thereafter tin or tin alloy may he applied on saidsurface by any desired method, a. very satisfactory adherence heing thusobtained.

What I claim as my invention and desire to secure by United StatesLetters Patent is:

l. A method for-coating with tin and tin alloys articles made ofaluminium. and aluminium alloys, consisting in coating said aluminiumarticle with an iron layer by electrolytic method, and then applying tinor tin alloy on said iron coating.

2. A. method for coating with tin and tin alloys articles made ofaluminium and aluminium alloys, consisting in treating said aluminiumarticle in an electrolytic hath of ferric sulfate to coat it with aniron layer, and then applying tin or tin alloy on said layer.

3. A method for coating with tin and tin alloys articles made ofaluminium and aluminium alloys, consisting in placing said aluminiumarticle in a bath comprisim equal amounts of a 4 per cent. solution 0ferric sulfate and of a 2 per cent. solution of ammonium oxalate,connecting said article with the negative terminal of a source ofelectric current having a strength of 0.15-

anipere for each square deciineter of surface to be coated, placmg insaid solution an iron plate connected with the positive terminal of saidsource to cause said current to circulate through said bath and toobtain an electrolytic iron layer on said article, washing and dryingsaid layer and applying tin or tin alloy thereon.

4. A. method for coating with tin and tin alloys articles made ofaluminium and aluminium alloys, consisting in placin said aluminiumarticle in a solution of ferric sulfate and ammonium oxalate, connectingsaid article with the negative terminal of an electriccurrent source,placing in said solution an iron plate connected with the positiveterminal of said source to cause said current to circulate through saidsolution, and obtain an electrolytic iron layer on said article, washingand drying said layer and applying tin or tin alloy thereon.

Signed at Turin, Italy, this 17th day of @ctober, A. l). 1918.

MICHELE ll. SALVATL liatented Mar. 2, Application filed November l5,1918. Serial No. 262,708.

